1. Field of the Invention
The present invention concerns a device which is capable of securing an element for rotation within a tube or cylinder such as, for example, an elongate tube of a multitubular heat exchanger, a steam condenser, or the like.
2. Description of the Related Art
Devices are known which are capable of continuously cleaning the internal surfaces of such tubes so as to improve heat transfer by reducing the thickness of the laminar layer which is in contact with the inner walls of the tube, as well as by increasing the Reynolds number. One such device makes use of an Archimedes' screw which is mounted for rotation in the tube responsive to the circulation of fluid through the tube. Such a device is disclosed, for example, in U.S. Pat. No. 4,174,750. According to this patent, an Archimedes' screw is retained in the tube of a heat exchanger by a swivel mounting which is secured in place by a hollow stopper comprised of a bearing flange and a support constituted by a metallic wire. The support is generally V-shaped, with its legs inserted in the flange of the stopper and its tip forming a hooking ring for securing a conventional swivel to the support.
This method of attachment has been found to present several drawbacks, one particular drawback being projection of the attachment from the plate which is used to secure the tubes in desired position (the tube plate); as a result of the bearing flange of the stopper resting on the tube plate, and projection of at least portions of the swivel from the bearing flange in view of its attachment to the apex of the V-shaped support. Projection of the attachment from the tube plate prohibits the use of such Archimedes' screws with devices which must move across the tube plate, such as inspection devices for verifying that the connection between each of the tubes and the tube plate remains waterproof, since the surface of the tube plate must be smooth for such operations to proceed.
It is therefore a primary objective of the present invention to provide a device which is capable of attaching an element for rotation in a tube without in any way projecting from the adjacent tube plate.
Another drawback encountered in the use of such attachment devices arises when the fluid (generally water) circulating inside the tubes is not completely free of impurities, but rather contains, for example, vegetable waste. These impurities can collect on the swivel (hook) or the support wire, eventually limiting the passage of fluid and/or inhibiting rotation of the cleaning device either mechanically, or by blocking the mouth of the tube.
It is therefore another objective of the present invention to provide a self-cleaning attachment device, which will accommodate vegetable or other wastes which are present in the fluid circulating inside the tubes.
A further objective of the present invention is to provide an attachment device which allows the effect of the Archimedes' screw to reach even the mouth of the tube, by ensuring appropriate turbulence even in those portions of the tube which do not actually contain a portion of the Archimedes' screw, so as to prevent the clogging of such regions as well.
A further objective of the present invention is also to provide an attachment device which is simply and rapidly assembled, even in connection with industrial applications wherein large series of tubes (up to 100,000 pieces) are combined in a single apparatus.